U.S. Pat. No. 4,581,429 discloses a free radical polymerization process for suitable unsaturated monomers utilizing an initiator of the structure (R.sup.1 R.sup.2 R.sup.3 C--) (R.sup.4 R.sup.5 R.sup.6 C--)N--O--X where X is a group comprising at least one carbon atom and is such that the free radical X is capable of polymerizing the unsaturated monomer by conventional free radical polymerization, and the radical functionality resides on the or one of the carbon atoms, and the groups R.sup.1, R.sup.2, R.sup.5 and R.sup.6 are the same or different straight chain or branched substituted or unsubstituted alkyl groups of a chain length sufficient to provide steric hindrance and weakening of the O--X bond, and R.sup.3 and R.sup.4 are the same or different straight chain or branched alkyl or substituted alkyl groups or R.sup.3 CNCR.sup.4 may be part of a cyclic structure which may have fused with it another saturated or aromatic ring. No molecular weight distribution less than 1.6 is reported.
Z. Florjanczyk and M. Siudakiewicz, J. Polym. Sci., Part A, Polym. Chem., 24(8), 1849-62, 1986, disclose the polymerization of vinyl monomers initiated by organoaluminum compounds/benzoyl peroxide systems. The free-radical polymerization of methyl methacrylate, acrylonitrile, vinyl acetate and styrene was initiated by systems comprising benzoyl peroxide and different organoaluminum compounds.
Japanese Patent No. 49032669, 2 Sep. 2, 1974, discloses polymerizing vinyl acetate in the presence of a catalyst system comprising a trialkylaluminum compound, an organic peroxide, and, optionally, zinc chloride. The catalyst was prepared in the presence of the vinyl monomer. Aluminum compounds included triethylaluminum, triisopropylaluminum, triisobutylaluminum and trihexylaluminum. Peroxides included benzoyl peroxide, peroxyoctanoic acid and dicumyl peroxide.
German Patent DE 1806940, Jul, 9, 1970 discloses catalysts for the polymerization of unsaturated monomers. Monomers comprised ethylenic compounds, e.g., ethylene, iso-butyl vinyl ether, acrylonitrile, vinyl acetate, styrene or methyl methacrylate. Catalysts consisted of triethylaluminum, an alkali or alkali earth halide, e.g., zinc chloride, and a gem-polyhalo compound, e.g., CCl.sub.4 or CCl.sub.3 CO.sub.2 Et.